Abstract: A spectroscopic analysis has been undertaken for the B-type multiple systems
(excluding those with supergiant primaries) in the VLT-FLAMES Tarantula Survey
(VFTS). Projected rotational velocities, $v$sin$i$, for the primaries have been
estimated using a Fourier Transform technique and confirmed by fitting
rotationally broadened profiles. A subset of 33 systems with $v$sin$i$$\leq$ 80
km/s have been analysed using a TLUSTY grid of model atmospheres to estimate
stellar parameters and surface abundances for the primaries. The effects of a
potential flux contribution from an unseen secondary have also been considered.
For 20 targets it was possible to reliably estimate their effective
temperatures (T$_{eff}$) but for the other 13 objects it was only possible to
provide a constraint of 20,000$\leq$T$_{eff}$$\leq$26,000 K -- the other
parameters estimated for these targets will be consequently less reliable. The
estimated stellar properties are compared with evolutionary models and are
generally consistent with their membership of 30 Doradus, while the nature of
the secondaries of 3 SB2 system is discussed. A comparison with a sample of
single stars with $v$sin$i$$\leq$ 80 km/s obtained from the VFTS and analysed
with the same techniques implies that the atmospheric parameters and nitrogen
abundances of the two samples are similar. However, the binary sample may have
a lack of primaries with significant nitrogen enhancements, which would be
consistent with them having low rotational velocities and having effectively
evolved as single stars without significant rotational mixing. This result,
which may be actually a consequence of the limitations of the pathfinder
investigation presented in this paper, should be considered as a motivation for
spectroscopic abundance analysis of large samples of binary stars, with high
quality observational data.